Periodic event recorders are previously known, having been disclosed for example in the following U.S. Pat. Nos.: 2,179,168; 3,818,858; 4,241,943; 4,752,087; 4,815,767; and 4,830,407.
U.S. Pat. Nos. 2,179,168, 4,241,943, 4,752,087 and 4,830,407 all disclose the use of cards or labels comprising a substrate and an overlying mask such as a sticker or coating that is scraped away or otherwise removed in conjunction with the performance or occurrence of a periodic event. Indicia identifying desired periodic intervals by one-to-one correspondence or some other similarly useful criteria are applied to either the substrate or the masking material. If applied to the substrate, the masking material is removed in conjunction with performance or occurrence of the periodic event to reveal the underlying indicia. If applied as part of the masking material, the masking material is removed in conjunction with performance or occurrence of the periodic event to reveal a contrasting substrate, thereby evidencing, for example, performance of a desired task.
U.S. Pat. No. 3,818,858 discloses means for indicating the date on which food products or other perishable material are placed into a container for subsequent refreshing of the memory of a housewife when looking into a refrigerator.
U.S. Pat. No. 4,815,767 discloses apparatus for use in taking medicine at periodic intervals that indicates the times of the day, days of the week and type of medication that should be taken. Distinctively shaped and/or colored stickers are desirably applied to a chart marked with appropriate periodic indicia, and matching stickers are applied to the corresponding medicament.
Notwithstanding the periodic event recorders previously disclosed, however, a periodic event recorder is needed that is simplistic in design, that can be easily attached to an object related to occurrence of a periodic event or the performance of a desired task, and that can be conveniently marked to clearly indicate occurrence of the event or performance of the task.